As sensor-based technology has improved dramatically in recent years, new uses for sensors and, specifically, cameras, have become possible. Applications of cameras include use in vehicle safety and autonomous or assisted driving systems. For many of these applications, it is desirable to deploy the camera in a configuration that minimizes interference with either other vehicle systems or with the driver's field of view. As a result, vehicle designers have been seeking to reduce camera sizes and identify optimal camera placement locations.
One type of camera that may be utilized in many applications is a thermal infrared camera. Thermal infrared (IR) cameras capture image wavelengths in the range of seven and a half to fourteen micrometers. A typical IR camera uses an infrared sensor to detect electromagnetic waves of the infrared spectrum which lie outside of the visible light range, which are guided to the sensor through the camera's lens. IR cameras can be utilized for a variety of imaging applications including, but not limited to, passive motion detection, night vision, thermal mapping, health care, building inspection, surveillance, and the like. Recently, an attempt has been made in the IR industry to integrate IR cameras in advanced driver assistance systems and autonomous vehicle systems.
One type of IR sensor is an uncooled far infrared (FIR) sensor with a small form factor. Due to recent technological advances, e.g., advanced wafer level packaging, such sensors can be mass-produced at low-cost. In a typical arrangement, an uncooled FIR sensor does not require a cryocooler for proper operation, but does require a shutter to correct fixed pattern noises, which occur in response to ambient temperature changes, as well as slow changes in sensing materials.
While using a shutter may improve the quality and accuracy of the thermal image captured by an IR sensor, having a blackout period of tenths of a second is not acceptable in certain applications. For example, using a shutter-based FIR camera in advanced driver assistance systems and autonomous vehicle systems can pose a high risk, as the camera must frequently shut off for a few hundreds of milliseconds. In addition, shutters include moving parts that wear out over time. This may cause a camera malfunction during driving and shorten the life time of the camera.
Further, a shutter adds to the size and weight of a camera. Of particular interest for driver assistance and other vehicle systems is proper placement of a camera while minimizing interference with, for example, the view of the driver or other automotive systems. Further, it is desirable to be able to conveniently remove obstructions, such as icing and fogging from the camera or any layer placed between the camera and the scene to be captured, particularly for IR cameras.
It would therefore be advantageous to provide a solution that would overcome the challenges noted above.